Can't Climax

Sorry in advance for TMI. I've been with 3 different partners and my current one for 2 years. The sex is great but I can never actually climax. We've tried multiple positions and a cock ring and still nothing. The only time I can orgasm is if I'm alone and watching porn. I am sexually attracted to him and I was to my previous partners so I don't know why it's not happening. Any answers or suggestions please????